Organic light emitting diode display and driving method thereof

ABSTRACT

A liquid crystal display device includes: a liquid crystal panel including red, green, and blue subpixels and a viewing angle control subpixel, wherein the viewing angle control subpixel includes a lower transparent electrode formed between a shielding electrode and an upper transparent electrode, the lower transparent electrode is formed on the first substrate and connected to the upper transparent electrode, the lower transparent electrode overlaps with the shielding electrode with a first insulation film interposed therebetween to form a storage capacitor.

This application claims the benefit of Korea Patent Application No.10-2009-0082686, filed on Sep. 2, 2009, the entire contents of which isincorporated herein by reference for all purposes as if fully set forthherein.

BACKGROUND

1. Field of the Invention

This disclosure relates to a liquid crystal display device and amanufacturing method thereof.

2. Discussion of the Related Art

The importance of a flat panel display (FPD) has been emphasizedfollowing the development of multimedia technologies. In response tothis trend, various flat type displays such as a liquid crystal display,a plasma display panel, and an organic field emission display have beenput to practical use. Among them, some display devices, e.g., liquidcrystal display devices and organic field emission displays, havedevices and wires formed in a thin film shape on a substrate bydeposition, etching, and so on.

The driving principle of liquid crystal display devices utilizes opticalanisotropy and polarization properties of liquid crystal. Liquid crystalhas directionality in the alignment its molecules due to its slender andlong structure. Hence, it is possible to control the orientation of theliquid crystal molecules by artificially applying an electric field tothe liquid crystal. Accordingly, by arbitrarily controlling thearrangement direction of the liquid crystal molecules, the alignment ofthe liquid crystal molecules is changed, so that an incident light isrefracted in the alignment direction of the liquid crystal molecules byoptical anisotropy to thereby display image information.

A liquid crystal display device includes a color filter substrate havinga common electrode formed thereon, an array substrate having pixelelectrodes formed thereon, and liquid crystal filled between the twosubstrates. Among liquid crystal display devices, a vertical electricfield emission display device which vertically applies an electric fieldbetween the common electrode and the pixel electrodes has hightransmittance and high aperture ratio, but has poor viewing angle. Manymethods were suggested to solve the above-mentioned problems, and oneexample thereof is a horizontal electric field emission display device.However, a horizontal electric field emission display device shows lesschange in birefringence depending on a viewing angle direction so thatit can have an improved viewing angle characteristic compared to thevertical electric field emission display device.

Recently, a liquid crystal display device that implements a viewingangle control method has been suggested in order for a user toselectively drive a wide viewing angle mode and a narrow viewing anglemode when working on a document which is important for security reasons.However, a conventional liquid crystal display device has a thickinsulating layer region formed thereon due to structural andmanufacturing process reasons and a deviation in the critical dimension(CD) of a pixel functioning to control viewing angle becomes larger tothereby reduce the aperture ratio and restrict the narrow viewing anglecharacteristic, and thus an improvement thereof is required.

BRIEF SUMMARY

A liquid crystal display device including: a liquid crystal panelincludes red, green, and blue subpixels and a viewing angle controlsubpixel, wherein the viewing angle control subpixel includes a lowertransparent electrode formed between a shielding electrode and an uppertransparent electrode, the lower transparent electrode being formed onthe first substrate, and connected to the upper transparent electrode,the lower transparent electrode and the shielding electrode overlap witha first insulation film interposed therebetween to form a storagecapacitor.

In another aspect, a manufacturing method of a liquid crystal displaydevice, includes: defining areas for red, green, and blue subpixels andan area for a viewing angle control subpixel on a first substrate;forming gate lines; forming a shielding electrode in the area of theviewing angle control subpixel; forming a first insulation film on thegate lines; forming data lines crossing the gate lines; forming a lowertransparent electrode on the first insulation film to overlap with theshielding electrode and forming a pixel electrode on the firstinsulation film formed in the areas for the red, green, and bluesubpixels; forming a second insulation film on the lower transparentelectrode and the pixel electrode; and forming a upper transparentelectrode connected to the lower transparent electrode on the secondinsulation film in the area for the viewing angle control subpixel andforming a lower common electrode having a plurality of segments on thesecond insulation film in the areas for the red, green, and bluesubpixels.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated on and constitute apart of this specification illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a block diagram for schematically explaining a liquid crystaldisplay device;

FIG. 2 is a plane view schematically showing a liquid crystal panelaccording to one exemplary embodiment of the present invention;

FIG. 3 is a cross sectional view explaining a driving mode of subpixelsshown in FIG. 2;

FIG. 4 is a plane view schematically showing a viewing angle controlsubpixel according to one exemplary embodiment of the present invention;

FIG. 5 is a cross sectional view of area A-B of FIG. 4;

FIG. 6 is a cross sectional view of area C-D of FIG. 4;

FIG. 7 is a cross sectional view of area E-F of FIG. 4;

FIG. 8 is a cross sectional view of area G-H of FIG. 4;

FIG. 9 is a cross sectional view of the viewing angle control subpixel;

FIG. 10 is a view for explaining a difference between a comparativeexample and an exemplary embodiment.

FIGS. 11 to 16 are plane views for explaining a manufacturing methodaccording to one exemplary embodiment of the present invention;

FIG. 17 is a view showing a black matrix layer on the plane view of FIG.16.

DETAILED DESCRIPTION OF THE DRAWINGS AND THE PRESENTLY PREFERREDEMBODIMENTS

Reference will now be made in detail embodiments of the inventionexamples of which are illustrated in the accompanying drawings.

Hereinafter, an implementation of this invention will be described indetail with reference to the accompanying drawings.

Referring to FIG. 1, the liquid crystal display device includes a liquidcrystal panel 10, a data driving circuit 12 connected to data linesD1˜Dm of the liquid crystal panel 10, a gate driving circuit 13connected to gate lines G1˜Gn of the liquid crystal panel 10, a timingcontroller 11 for controlling the data driving circuit 12 and the gatedriving circuit 13, and a power supply unit 15 for generating power.

The liquid crystal panel 10 includes a first substrate and a secondsubstrate adhered together with a liquid crystal layer interposedtherebetween. A pixel array of the first substrate includes thin filmtransistors formed at the crossing portions of the data lines D1˜Dm andthe gate lines G1˜Gn and pixel electrodes connected to the thin filmtransistors. Each of the liquid crystal cells of the pixel array isdriven by a voltage difference between a data voltage which is appliedto the pixel electrode through the thin film transistors and a commonvoltage applied to a common electrode, and adjusts the amount oftransmission of light incident from a backlight unit 16 to display animage of video data. A black matrix layer, a color filter layer, and thecommon electrode are formed on the second substrate. By the way, thecommon electrode may be respectively formed on each of the first andsecond substrates according to a driving method. A polarizer is formedon each of the first and second substrates of the liquid crystal panel10, and an alignment film for setting a pre-tilt angle of liquid crystalis formed thereon.

A system board 14 transmits, along with RGB video data input from abroadcasting receiving circuit or an external video source, systemsignals, such as a vertical synchronization signal (Vsync), a horizontalsynchronization signal (Hsync), a data enable signal (DE), and a dotclock (CLK), to the timing controller 11 through an LVDS (Low VoltageDifferential Signaling) interface transmitting circuit or a TMDS(Transition Minimized Differential Signaling) interface transmittingcircuit.

The power supply unit 15 adjusts a voltage Vin supplied to the systemboard 14 to generate a driving voltage, and supplies the generateddriving voltage to at least one of the timing controller 11, the datadriving circuit 12, the gate driving circuit 13, and the liquid crystalpanel 10. The power supply unit 15 is formed as a DC-DC converter. Thedriving voltage generated by the power supply unit 15 includes a powersupply voltage Vdd, a logic power supply voltage Vcc, a gate highvoltage VGH, a gate low voltage VGL, a common voltage Vcom, andpositive/negative gamma reference voltages VGMA1˜VGMA10.

The timing controller 11 receives system signals, such as timing signalsincluding a vertical synchronization signal Vsync, a horizontalsynchronization signal Hsync, a data enable signal DE, and a dot clockCLK, through an LVDS (Low Voltage Differential Signaling) interfacereceiving circuit or a TMDS (Transition Minimized DifferentialSignaling) interface receiving circuit. The timing controller 11generates driving signals, such as data control signals SSC, SOE, andPOL to control the data driving circuit and gate signals, such as timingcontrol signals GSP, GSC, and GOE to control the operation timing of thegate driving circuit 13 by using timing signals Vsync, Hsync, DE, andCLK.

The data driving circuit 12 samples and latches RGB digital video dataRGB in accordance with RGB data of a mini LVD interface specificationand a mini LVDS clock from the timing controller 11 and changes theminto data of a parallel data format. In response to a polarity controlsignal POL, the data driving circuit 12 converts the digital video data,which are converted into a parallel data format, into positive/negativeanalog video data voltages for charging the liquid crystal cells byusing positive/negative gamma reference voltage VGMA1˜VGMA10.

The gate driving circuit 13 includes a shift register that sequentiallyshifts a gate driving voltage in response to gate timing signals GSP,GSC, and GOE from the timing controller 11 to sequentially supply gatepulses (or scan pulses) to the gate lines G1˜Gn.

Referring to FIG. 2, the liquid crystal display device according to oneexemplary embodiment of the present invention includes a liquid crystalpanel 110 having red, green, and blue subpixels Sp1˜Sp3 and a viewingangle control subpixel Sp4 which are arranged in a quad type to form oneunit pixel. The red, green, and blue subpixels Sp1˜Sp3 operate in an FFS(Fringe Field Switching) mode, and the viewing angle subpixel Sp4operates in an ECB (Electrically Controlled Birefringence) mode.However, the red, green, and blue subpixels Sp1˜Sp3 may be implementedso as to operate in an IPS (In-Plane Switching) mode. Although the shapeof the subpixels Sp1˜Sp3 is briefly illustrated in the drawings, thesubpixels Sp1˜Sp3 are disposed within the second substrate adhered tothe first substrate and driven by the thin film transistors connected tothe gate lines and the data lines.

Referring to FIG. 3, the viewing angle control subpixel Sp4 includes anupper transparent electrode 121 which is formed on first and secondinsulation films 113 and 119 formed on the first substrate 110 a.Further, the viewing angle control subpixel Sp4 includes an upper commonelectrode 157 which is formed on an overcoating layer 155 formed on thesecond substrate 110 b. The upper common electrode 157 may be formedalong the black matrix layer 151. The upper common electrode 157 isformed on an outer circumference of the second substrate 110 b andconnected to a common voltage line formed on the first substrate 110 aby a conductive ball or a silver dot when bonding the second substrate110 b and the first substrate 110 a together. Here, the common voltageline may be divided into a common voltage line for supplying the samecommon voltage to the red, green, and blue subpixels Sp1, Sp2, and Sp3and the viewing angle control subpixel Sp4 and a common voltage line forsupplying a common voltage to the upper common electrode 157.Alternatively, one common voltage line may be used. For the viewingangle control subpixel Sp4, when a data voltage and a common voltage aresupplied to the upper transparent electrode 121 and the upper commonelectrode 157, a potential difference is generated between them to thusraise a liquid crystal layer 131 in the illustrated electric fielddirection 133. At this point, light incident in a vertical direction ofthe first substrate 110 a is not transmitted because there is no changein polarization. Thus, light incident to the viewing angle controlsubpixel Sp4 appears in black on the front surface of the liquid crystalpanel. On the contrary, light incident in a diagonal direction of thefirst substrate 110 a is polarized and transmitted by the liquid crystallayer 131. Therefore, the light incident to the viewing angle controlsubpixel Sp4 appears in white on a side surface of the liquid crystalpanel.

On the other hand, the blue subpixel Sp3 includes a pixel electrode 115formed between first and second insulation films 113 and 119 formed onthe first substrate 110 a and a lower common electrode 124 formed on thesecond insulation film 119 and divided into a plurality of segments.Further, the blue subpixel Sp3 includes a color filter layer 153 whichcovers the black matrix layer 151 formed on the second substrate 110 b.For the blue subpixel Sp3, when a data voltage and a common voltage aresupplied to the pixel electrode 115 and the lower common electrode 124,a potential difference is generated between them to thus allow a liquidcrystal layer 131 to rotate in the illustrated electric field direction133 by a fringe field effect. At this point, the light passed throughthe first substrate 110 a is polarized and transmitted. Therefore, thelight incident to the blue subpixel Sp3 appears in blue on the liquidcrystal panel.

Hereinafter, the subpixels disposed on the liquid crystal panel will bedescribed in more detail.

Referring to FIG. 4, there are illustrated the red subpixel Sp1, thegreen subpixel Sp2, the blue subpixel Sp3, and the viewing angle controlsubpixel Sp4. The illustrated subpixels Sp1, Sp2, Sp3, and Sp4respectively include thin film transistors TFTs connected to the datalines 117 and the gate lines 111, respectively. The viewing anglecontrol subpixel Sp4 includes a lower transparent electrode 116overlapping with a shielding electrode 112 and an upper transparentelectrode 121 connected to the lower transparent electrode 116 and thedrain 117 b of the thin film transistor TFT. The upper transparentelectrode 121 is connected to the lower transparent electrode 116 andthe drain 117 b of the thin film transistor TFT through a first contacthole CH1, and is supplied with a data voltage through the drain 117 b.The red, green, and blue subpixels Sp1, Sp2, and Sp3 are formed to sharethe lower common electrode 124 to which a common voltage is supplied.The lower common electrode 124 of the red, green, and blue subpixelsSp1, Sp2, and Sp3 is connected to the shielding electrode 112 of theviewing angle control subpixel Sp4 through a second contact hole CH2.Hereinafter, the structure of the subpixels Sp1, Sp2, Sp3, and Sp4 willbe described with reference to the respective cross sectional views.

Referring to FIGS. 4 and 5, there are illustrated the cross sectionalviews of the viewing angle control subpixel Sp4 and the blue subpixelSp3. The shielding electrode 112 is formed in a spaced-apart andopposing fashion on the first substrate 110 a defined as the area of theviewing angle control subpixel Sp4. Further, the gate line 111 includinga gate electrode 111 a is formed on the first substrate 110 a defined asthe area of the viewing angle control subpixel Sp4. The gate line 111including a gate electrode 111 a is formed on the first substrate 110 adefined as the area of the blue subpixel Sp3. The shielding electrode112 and gate line 111 of the viewing angle control subpixel Sp4 and thegate line 111 of the blue subpixel Sp3 are formed of the same materialby the same process. The first insulation film 113 is formed on the areaof the viewing angle control subpixel Sp4 so as to cover the shieldingelectrode 112 and the gate line 111, and the first insulation film 113is formed on the area of the blue subpixel Sp3 so as to cover the gateline 111. The lower transparent electrode 116 is formed on the firstinsulation film 113 so as to overlap with the shielding electrode 112formed in the area of the viewing angle control subpixel Sp4. The pixelelectrode 115 formed on the area of the blue subpixel Sp3 is formed onthe first insulation film 113. The lower transparent electrode 116 andthe pixel electrode 115 are formed of the same material by the sameprocess, and are patterned so as to be separated from each other. Thedata lines 117 defining the viewing angle control subpixel Sp4 and theblue subpixel Sp3, respectively, are formed on the first insulation film113. The second insulation film 119 is formed on the areas of theviewing angle control subpixel Sp4 and the blue subpixel Sp3 so as tocover the lower transparent electrode 116, the pixel electrode 115, andthe data lines 117. The upper transparent electrode 121 is formed on thesecond insulating film 119 in the area of the viewing angle controlsubpixel Sp4. The lower common electrode 124 divided into a plurality ofsegments is formed on the second insulation film 119 in the area of theblue subpixel Sp3.

Referring to FIGS. 4 and 6, there is illustrated the thin filmtransistor TFT of the viewing angle control subpixel Sp4. The gateelectrode 111 a connected to the gate line 111 supplied with a gatepulse is formed on the first substrate 110 a. The shielding electrode112 separated from the gate electrode 111 a and supplied with a commonvoltage is formed on the first substrate 110 a. The first insulationfilm 113 is formed on the gate electrode 111 a and the shieldingelectrode 112. An active layer 114 is formed on the first insulationfilm 113, corresponding to the gate electrode 111 a. The lowertransparent electrode 116 is formed on the first insulation film 113,corresponding to the shielding electrode 112. A source electrode 117 aconnected to the data line 117 supplied with a data voltage is formed onone side of the active layer 114. The drain electrode 117 b connected tothe lower transparent electrode 116 is formed on the other side of theactive layer 114. The second insulation film 119 is formed on the firstinsulation film 113 so as to cover the source electrode 117 a and thedrain electrode 117 b. The first contact hole CH1 exposing part of thelower transparent electrode 116 is formed in the second insulation film119. The upper transparent electrode 121 connected to the lowertransparent electrode 116 through the first contact hole CH1 is formedon the second insulation film 119.

Referring to FIGS. 4 and 7, there is illustrated the shielding electrode112 and the lower common electrode 124 connected each other through thesecond contact hole CH2 on the viewing angle control subpixel Sp4. Theshielding electrode 112 and the gate line 111 are formed on the firstsubstrate 110 a. The first insulation film 113 is formed on the firstsubstrate 110 a so as to cover the shielding electrode 112 and the gateline 111. The lower transparent electrode 116 is formed on the firstinsulation film 113 so as to overlap with the shielding electrode 112.The second insulation film 119 is formed on the first insulation film113 so as to cover the lower transparent electrode 116. The secondcontact hole CH2 exposing part of the shielding electrode 112 is formedin the second insulation film 119. The lower common electrode 124 isformed on the second insulation film 119 so as to be connected to theshielding electrode 112 through the second contact hole CH2 andprojected toward the neighboring blue subpixel Sp3. The uppertransparent electrode 121 of the viewing angle control subpixel Sp4 isformed on the second insulation film 119 so as to be separated from thelower common electrode 124 of the blue subpixel Sp3. The lower commonelectrode 124 and the upper transparent electrode 121 are formed of thesame material by the same process.

Referring to FIGS. 4 and 8, there is illustrated the thin filmtransistor TFT of the blue subpixel Sp3. The gate electrode 111 aconnected to the gate line 111 supplied with a gate pulse is formed onthe first substrate 110 a. The first insulation film 113 is formed onthe gate electrode 111 a. The active layer 114 is formed on the firstinsulation film 113, corresponding to the gate electrode 111 a. Thepixel electrode 115 is formed on the first insulation film 113. Thesource electrode 117 a connected to the data line 117 supplied with adata voltage is formed on one side of the active layer 114. The drainelectrode 117 b connected to the pixel electrode 115 is formed on theother side of the active layer 114. The second insulation film 119 isformed on the first insulation film 113 so as to cover the sourceelectrode 117 a and the drain electrode 117 b. The lower commonelectrode 124 divided into a plurality of segments is formed on thesecond insulation film 119. When a potential difference is generatedbetween the data voltage supplied to the pixel electrode 115 and thecommon voltage supplied to the lower common electrode 124, the bluesubpixel Sp3 operates in the FFS mode in which the liquid crystal layerrotates in an electric field direction by the fringe field effect. Here,the subpixels operating in the FFS mode include the red and greensubpixels Sp1 and Sp2 as well as the blue subpixel Sp3. While theexemplary embodiment has been described with respect to a case where thered, blue, and green pixels Sp1, Sp2, and Sp3 operate in the FFS mode,this exemplary embodiment may be implemented so that they operate in theIPS mode.

Hereinafter, the viewing angle control subpixel according to oneexemplary embodiment of the present invention will be described.

Referring to FIG. 9, in the viewing angle control subpixel SP4 accordingto one exemplary embodiment of the present invention, the lowertransparent electrode 116 connected to the upper transparent electrode121 and the shielding electrode 112 form a storage capacitor Cst withthe first insulation film 113 interposed therebetween. The structure ofthe viewing angle control subpixel Sp4 will be described in more detailbelow. However, illustration of the liquid crystal layer is omitted. Theshield electrode 112 is formed on the first substrate 110 a. A commonvoltage is supplied to the shield electrode 112. As shown in FIG. 4, theshielding electrode 112 is formed so as to occupy at least three sideswithin the area of the viewing angle control subpixel Sp4 and have twopatterns spaced from each other and parallel to each other. The firstinsulation film 113 is formed on the shielding electrode 112. The lowertransparent electrode 116 is formed on the first insulation film 113 tooverlap with the shielding electrode 112. The data line 117 is formed onthe first insulation film 113. Similarly to the shielding electrode 112,the lower transparent electrode 116 is formed so as to occupy at leastthree sides within the area of the viewing angle control subpixel Sp4and have two patterns are spaced from each other and parallel to eachother. The second insulation film 119 covering the lower transparentelectrode 116 is formed on the first insulation film 113 so as to exposepart of the lower transparent electrode 116. The upper transparentelectrode 121 connected to the lower transparent electrode 116 throughthe first contact hole CH1 is formed on the second insulation film 119.The upper transparent electrode 121 is formed to partially overlap withthe three sides of the shielding electrode 112 and of the lowertransparent electrode 116 within the area of the viewing angle controlsubpixel Sp4. The black matrix layer 151 defining the areas of thesubpixels is formed on the second substrate 110 b. The black matrixlayer 151 may include a photosensitive organic material to which blackpigment is added, such as, but not limited to, carbon black or titaniumoxide. The overcoating layer 155 covering the black matrix layer 151 isformed on the second substrate 110 b. The overcoating layer 155 mayinclude an organic material, an inorganic material, or a mixturethereof. The upper common electrode 157 is formed on the overcoatinglayer 155. The upper common electrode 157 is formed corresponding to theupper transparent electrode 121 within the area of the viewing anglecontrol subpixel Sp4.

In the above-described exemplary embodiment, when a potential differenceis generated between the data voltage supplied to the lower and uppertransparent electrodes 116 and 121 and the common voltage supplied tothe upper common electrode 157, the viewing angle control subpixel Sp4operates in the ECB mode in which the liquid crystal layer is raised inan electric field direction. In the exemplary embodiment, when thenarrow viewing angle mode is applied in the liquid crystal panel, thelower and upper transparent electrodes 116 and 121 are electricallyconnected in order to increase the aperture ratio of the viewing anglecontrol subpixel Sp4, and, along with the shielding electrode 112, forma storage capacitor Cst. Therefore, the viewing angle control subpixelSp4 of the exemplary embodiment can increase the aperture ratio whileincreasing the capacitance of the storage capacitor Cst.

Referring to FIG. 10, there are illustrated a comparative example Refand an exemplary embodiment Emb. In the structure of the comparativeexample Ref, the shielding electrode 112 supplied with a common voltageand the upper transparent electrode 121 supplied with a data voltageform a storage capacitor Cst with the first and second insulation films113 and 119 interposed therebetween. In the structure of the comparativeexample Ref, the area occupied by the shielding electrode 112 has to beincreased in order to compensate for a decrease of the capacitance ofthe storage capacitor Cst due to the thickness of the insulation films113 and 119 formed between the shielding electrode 112 and the uppertransparent electrode 121. In this case, the non-aperture region NR isincreased by an increase in the critical dimension of the shieldingelectrode 112 as well as by an increase in the area occupied by theshielding electrode 112. Therefore, in the structure of the comparativeexample Ref, the area of the aperture region AR becomes smaller due tothe increase in the non-aperture region NR. As a result, the narrowviewing angle characteristic of the liquid crystal panel is restricted.

On the other hand, in the structure of the exemplary embodiment Emb, thelower transparent electrode 116 and upper transparent electrode 121supplied with a data voltage are formed on the first insulation film 113and the second insulation film 119, respectively, and they areelectrically connected to thus form a storage capacitor Cst along withthe shielding electrode 112. Therefore, in the structure of theexemplary embodiment Emb, the lower transparent electrode 116 and theshielding electrode 112 form the storage capacitor Cst with the firstinsulation film 113 interposed therebetween. In this case, the areaoccupied by the shielding electrode 112 can be decreased by 60% comparedto the comparative example Ref while maintaining the capacitance of thestorage capacitor Cst the same as in the structure of the comparativeexample Ref. Accordingly, in the structure of the exemplary embodimentEmb, the area of the aperture region AR can be increased compared to thecomparative example Ref, thereby improving the narrow viewing anglecharacteristic of the liquid crystal panel. Although the exemplaryembodiment has been described with respect to a case where thecapacitance of the storage capacitor Cst is maintained the same as inthe structure of the comparative example Ref, the area of the aperturearea AR can be increased while increasing the capacitance of the storagecapacitor Cst compared to the comparative example Ref.

Hereinafter, a manufacturing method of a liquid crystal display devicewill be described.

As shown in FIGS. 5 and 11, the gate line 111 including the gateelectrode 111 a is formed in the area of the viewing angle controlsubpixel Sp4 and the area of the blue subpixel Sp3, respectively. On thefirst substrate 110 a formed in the area of the viewing angle controlsubpixel Sp4, the shielding electrode 112 is formed which occupies atleast three sides within the area of the viewing angle control subpixelSp4 and has two patterns spaced from each other and parallel to eachother. The gate lines 111 and the shielding electrode 112 may be formedof the same material by the same process, but are not limited thereto.The gate lines 111 and the shielding electrode 112 may be a single layerformed of any one selected from the group consisting of molybdenum (Mo),aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni),neodymium (Nd), and copper (Cu), or a multilayer formed of one or moreof these materials, but are not limited thereto. Afterwards, the firstinsulation film 113 is formed in the area of the viewing angle controlsubpixel Sp4 so as to cover the gate line 111 and the shieldingelectrode 112, and the first insulation film 113 is formed in the areaof the blue subpixel Sp3 so as to cover the gate line 111. The firstinsulation film 113 may be formed of a silicon oxide film (SiOx), asilicon nitride film (SiNx), or a multilayer thereof, but is not limitedthereto.

As shown in FIGS. 5 and 12, the active layer 114 is respectively formedon the gate lines 111 formed in the area of the viewing angle subpixelSp4 and the area of the blue subpixel Sp3.

As shown in FIGS. 5 and 13, the lower transparent electrode 116 isformed in the area of the viewing angle control subpixel Sp4 so as tohave a region overlapping with the shielding electrode 112 formedthereunder. The pixel electrode 115 is formed in the area of the bluesubpixel Sp3. The pixel electrode 115 is formed so as to correspond tothe aperture region. The lower transparent electrode 116 and the pixelelectrode 115 may be formed of the same material by the same process,but are not limited thereto. The lower transparent electrode 116 and thepixel electrode 115 may be formed of ITO (Indium Tin Oxide), IZO (IndiumZinc Oxide), or ZnO (Zinc Oxide), but are not limited thereto.

As shown in FIGS. 5 and 14, the source electrode 117 a and the drainelectrode 117 b are formed on one side and the other side of the activelayer 114 formed in the area of the viewing angle control subpixel Sp4and the area of the blue subpixel Sp3. Here, the data lines 117 formedin the area of the viewing angle control subpixel Sp4 and the area ofthe blue subpixel Sp3 are formed by the same process as the sourceelectrodes 117 a. The drain electrode 117 b formed in the area of theviewing angle control subpixel Sp4 is connected to the lower transparentelectrode 116, and the drain electrode 117 b formed in the area of theblue subpixel Sp3 is connected to the pixel electrode 115. The sourceelectrodes 117 a and the drain electrodes 117 b may be a single layerformed of any one selected from the group consisting of molybdenum (Mo),aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni),neodymium (Nd), and copper (Cu), or a multilayer formed of one or moreof these materials, but are not limited thereto. Although the exemplaryembodiment has been described with respect to a case where the sourceand drain electrodes 117 a and 117 b are formed after the formation ofthe lower transparent electrode 116, the lower transparent electrode 116may be formed after the formation of the source and drain electrodes 117a and 117 b.

As shown in FIGS. 6, 7, and 15, the second insulation film 119 is formedso as to cover the source electrodes 117 a and the drain electrodes 117b that are formed in the area of the viewing angle control subpixel Sp4and the area of the blue subpixel Sp3. The first contact hole CH1exposing part of the drain electrode 117 b and the second contact holeCH2 exposing part of the shielding electrode 112 are formed in thesecond insulation film 119 formed in the area of the viewing anglecontrol subpixel Sp4. The second insulation film 119 may be formed of asilicon oxide film (SiOx), a silicon nitride film (SiNx), or amultilayer thereof, but is not limited thereto.

As shown in FIGS. 5 and 16, the upper transparent electrode 121 isformed on the second insulation film 119 formed in the area of theviewing angle control subpixel Sp4, and the upper transparent electrode121 is formed so as to correspond to the aperture region. The uppertransparent electrode 121 is formed so as to have a region overlappingwith the lower transparent electrode 116 formed thereunder, and isconnected to the lower transparent electrode 116 through the firstcontact hole CH1. The lower common electrode 124 is formed on the secondinsulation film 119 formed in the area of the blue subpixel Sp3. Thelower common electrode 124 is divided into a plurality of segmentswithin the aperture region, and is connected to the shielding electrode112 of the viewing angle control subpixel Sp4 through the second contacthole CH2.

Referring to FIG. 17, the viewing angle control subpixel Sp4 and theblue subpixel Sp3 manufactured by the process of FIG. 16 have theaperture regions as shown in the drawing by means of the black matrixlayer 151.

With the configuration as described above, quad type subpixels includingred and green subpixels, a color filter layer, etc. are formedrespectively on two substrates. And, the two substrates are adheredtogether by using an adhesive member to thus complete the liquid crystalpanel with the liquid crystal layer formed therebetween. While theexemplary embodiment of the present invention has been described withreference to a schematic view of one of the structures of the red,green, and blue subpixels in order to explain the structure of theelectrodes forming a storage capacitor Cst in the structure of theviewing angle control subpixel Sp4, the present invention is not limitedthereto.

As seen from above, the present invention can provide a liquid crystaldisplay device which can improve viewing angle control efficiency byincreasing the aperture ratio of the viewing angle control subpixel.Further, the present invention can provide a liquid crystal displaydevice which can reduce character readability from the direction of aviewing angle along with the improvement of viewing angle controlefficiency. Further, the present invention can provide a liquid crystaldisplay device which can increase the capacitance of the storagecapacitor.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures. Moreover, unlessthe term “means” is explicitly recited in a limitation of the claims,such as limitation is not intended to be interpreted under 35 USC 112(6).

1. A liquid crystal display device comprising: a liquid crystal panelincluding red, green, and blue subpixels and a viewing angle controlsubpixel, wherein the viewing angle control subpixel includes a lowertransparent electrode formed between a shielding electrode and an uppertransparent electrode, the lower transparent electrode being on a firstsubstrate, and connected to the upper transparent electrode, and whereinthe lower transparent electrode overlaps with the shielding electrodewith a first insulation film interposed therebetween to form a storagecapacitor.
 2. The liquid crystal display device of claim 1, wherein theviewing angle control subpixel comprises: a shielding electrode on thefirst substrate; a first insulation film on the shielding electrode; alower transparent electrode on the first insulation film; a secondinsulation film covering the lower transparent electrode disposed on thefirst insulation film with a part of the lower transparent electrodebeing exposed; and an upper transparent electrode on the secondinsulation film, and being connected to the lower transparent electrode.3. The liquid crystal display device of claim 1, wherein the shieldingelectrode and the lower transparent electrode have at least three sideswithin the area of the viewing angle control subpixel.
 4. The liquidcrystal display device of claim 1, wherein the three sides of theshielding electrode and the lower transparent electrode partiallyoverlap with each other within the area of the viewing angle controlsubpixel.
 5. The liquid crystal display device of claim 1, wherein theviewing angle control subpixel comprises: a black matrix layer on asecond substrate; an overcoating layer on the black matrix layer; and anupper common electrode on the overcoating layer.
 6. The liquid crystaldisplay device of claim 5, wherein the upper common electrodecorresponds to the upper transparent electrode within the area of theviewing angle control subpixel.
 7. The liquid crystal display device ofclaim 1, wherein the red, green, and blue subpixels compriserespectively a color filter layer on the second substrate.
 8. The liquidcrystal display device of claim 1, wherein the red, green, and bluesubpixels comprise respectively: a pixel electrode formed on the firstinsulation film; and a lower common electrode formed on the secondinsulation film and having a plurality of segments.
 9. The liquidcrystal display device of claim 8, wherein the lower common electrodeadjacent to the viewing angle control subpixel is connected to theshielding electrode.
 10. The liquid crystal display device of claim 1,wherein the red, green, and blue subpixels and the viewing angle controlsubpixel are arranged in a quad type.
 11. The liquid crystal displaydevice of claim 1, wherein the red, green, and blue subpixels operate inan FFS (Fringe Field Switching) mode, and the viewing angle controlsubpixel operates in an ECB (Electrically Controlled Birefringence)mode.
 12. A manufacturing method of a liquid crystal display device,comprising: defining areas for red, green, and blue subpixels and anarea for a viewing angle control subpixel on a first substrate; forminggate lines; forming a shielding electrode in the area of the viewingangle control subpixel; forming a first insulation film on the gatelines; forming data lines crossing the gate lines; forming a lowertransparent electrode on the first insulation film to overlap with theshielding electrode and forming a pixel electrode on the firstinsulation film formed in the areas for the red, green, and bluesubpixels; forming a second insulation film on the lower transparentelectrode and the pixel electrode; and forming a upper transparentelectrode connected to the lower transparent electrode on the secondinsulation film in the area for the viewing angle control subpixel andforming a lower common electrode having a plurality of segments on thesecond insulation film in the areas for the red, green, and bluesubpixels.
 13. The method of claim 12, wherein the shielding electrodeand the lower transparent electrode have at least three sides within thearea of the viewing angle control subpixel.
 14. The method of claim 12,wherein the three sides of the shielding electrode and the lowertransparent electrode partially overlap with each other within the areaof the viewing angle control subpixel.
 15. The method of claim 12,further comprising forming a second substrate to be adhered to the firstsubstrate, wherein the forming the second substrate comprises: definingareas for the red, green, and blue subpixels and an area for the viewingangle control subpixel on the second substrate; and forming a blackmatrix layer on the second substrate; and forming an overcoating layeron the black matrix layer.
 16. The method of claim 15, furthercomprising forming an upper common electrode on the overcoating layer inthe area for the viewing angle control subpixel.
 17. The method of claim16, wherein the upper common electrode is formed so as to correspond tothe upper transparent electrode within the area of the viewing angelcontrol subpixel.
 18. The method of claim 12, wherein the uppertransparent electrode is connected to the lower transparent electrodethrough a first contact hole formed in the second insulation film. 19.The method of claim 12, wherein the lower common electrode formedadjacent to the viewing angle control subpixel is connected to theshielding electrode through a second contact hole formed in the secondinsulation film.
 20. The method of claim 12, wherein the red, green, andblue subpixels and the viewing angle control subpixel are arranged in aquad type.